Species and climate change

Climate change is set to be one of the major drivers of species extinctions in the 21st century: approximately 20 to 30 per cent of plant and animal species are likely to be at increasingly high risk as global mean temperatures rise.

But which species will suffer the most? Which species, ecosystems and regions should we prioritize for conservation?

A recent IUCN report identifies 10 species that are most vulnerable to climate change. Find out what they are and learn what threats they face:

Arctic Foxes

The Arctic Fox is one of the top land-dwelling predators of the Arctic region. It is thought to be one of the first mammals to have colonised Sweden and Finland following the last ice-age.

As the Arctic region warms, tundra habitat may slowly be replaced by boreal forest from the South. Forest habitat is unsuitable for Arctic Foxes.

Red Foxes prey on and are superior hunters to Arctic Foxes. Northward encroachment of Red Foxes into the Arctic Fox’s range has already been documented and is likely to continue as the tundra warms.

Arctic Foxes prey largely on lemmings and voles. Milder and shorter winters are predicted to cause declines in the regularity of these rodents’ population cycles, as well as decreases in their overall numbers.

These factors are likely to cause declines in Arctic Fox numbers and range size. Arctic Foxes highlight the impacts of climate change on the ways that species interact with each other, both through competition and via changes in predator-prey relationships.

Clownfish

Clownfish live in tropical and subtropical ocean waters and have a mutualistic relationship with sea anemones, on which they rely for protection.

Coral reefs are seriously declining globally and time-lagged effects and increasing CO2 levels mean that rapid further declines are imminent. Clownfish and sea anemones depend on coral reefs for their habitat.

Clownfish are also affected by increasing ocean acidification. More acidic water disrupts their sense of smell, impairing their ability to find their specific host sea anemone.

There is some possibility that clownfish may adapt to these changes by changing their behaviour or the places they inhabit. However, their inability to move long distances and the rate at which their habitat is being degraded makes such an occurrence unlikely.

Clownfish highlight the impacts of coral reef degradation, increasing ocean acidification and warming oceans due to climate change. These changes directly or indirectly affect most species in the marine biome.

Koalas

Koalas are iconic animals native to Australia. They are true habitat and food specialists, only ever inhabiting forests and woodlands where Eucalyptus trees are present.

Increasing atmospheric CO2 levels will reduce the nutritional quality of Eucalyptus leaves, causing nutrient shortages in the species that forage on them. As a result, Koalas may no longer be able to meet their nutritional demands, resulting in malnutrition and starvation.

Increasing frequency and intensity of droughts can force Koalas to descend from trees in search of water or new habitats. This makes them particularly vulnerable to wild and domestic predators, as well as to road traffic.

Koala populations are reported to be declining due to malnutrition, the sexually-transmitted disease chlamydia, and habitat destruction.

Koalas have very limited capability to adapt to rapid, human-induced climate change, making them very vulnerable to its negative impacts.

Emperor Penguins

For much of the year, Emperor Penguins live on thick sea ice in the Antarctic, which they use for mating, chick rearing and moulting.

In some regions of the Antarctic, seasonal sea ice extent and thickness have reduced in recent decades following climate change. Continued warming will lead to further reductions in sea ice, impacting Emperor Penguins, with more northerly colonies being most at risk.

The biomass of Antarctic krill has decreased in recent decades correlating with decreases in sea ice. Changes in krill abundance are likely to negatively affect Emperor Penguins and many other Antarctic species.

Emperor Penguins highlight the possible impacts of rising sea temperatures and melting sea ice due to climate change. These changes directly or indirectly affect many other species in the Antarctic marine ecosystem.

Leatherback Turtles

The Leatherback Turtle is the largest of all the living turtles. Weighing in at over 500kg, it is often called the ‘gentle giant’ of the ocean.

Higher sand temperatures during egg incubation lead to disproportionately higher numbers of female turtles. Increasing sand temperatures caused by climate change could threaten the stability of Leatherback populations in the future.

Leatherbacks are listed as Critically Endangered on the IUCN’s Red List and face a number of threats, including accidental capture by fisheries, coastal development and consumption of plastic debris.

Leatherback Turtles highlight the impacts of increasing air and sea temperatures, rising sea levels and changing ocean currents. These changes are likely to affect all marine turtles and many other marine species.

Quiver Trees

The Quiver Tree, a long-lived giant tree Aloe, is iconic in the Namib Desert region of southern Africa. This region is projected to experience increasing droughts due to climate change.

The Quiver Tree seems to be responding to this warming by shifting its distribution range towards higher latitudes (closer to the poles) and higher altitudes (tops of mountains), where conditions are typically cooler and moister.

To keep up with a shifting climate, the Quiver Tree must, in time, colonise new pole-ward areas that are now becoming suitable. Sadly, no new populations have yet been found.

The Quiver Tree highlights the problems that all plants and slow-moving species face in keeping up with rapidly accelerating changing climate.

Salmon

Salmon have a long historical association with human society and make a large contribution to economies. They also have important ecological roles.

Some salmon populations have declined significantly in recent decades. While human activities are largely responsible, climate change could now exacerbate or even supersede these threats, particularly in the southern part of their natural range.

Although not well understood, impacts on salmon’s marine habitat could lead to temporal and spatial shifts in both their prey and predators. Possible changes to the timing of migration represents an important new threat.

These species highlight the effects of rising temperatures on both freshwater and marine ecosystems, and illustrate how climate change impacts on wild species can have a direct effect on economies.

Beluga Whales

Beluga whales live in Arctic and sub-Arctic waters and are sociable and vocal animals. They are hunted by indigenous Arctic people for food and are captured alive on a relatively small scale in eastern Russia to supply the live animal display industry throughout the world.

Climate change is likely to affect Belugas both directly through ecological interactions and indirectly through its effects on human activity.

Among the ecological factors that may affect Belugas are changes in populations of their prey, changes in ice conditions, greater competition with co-predators, more frequent predation by killer whales and exposure to novel pathogens.

As Arctic ice cover rapidly declines and the passages across northern landmasses become more navigable, humans will gain easier access to formerly pristine areas that have long served as refuges for Belugas and other marine mammals.

Belugas are increasingly at risk from vessel and industrial noise, ship strikes and toxin exposure.